"His actions breached caucus rules and were calculated to damage the party and the leadership," Mr Goff said. "That is unacceptable to me and to my caucus. Chris Carter has no future in the Labour Party that I lead."

Mr Carter was exposed as the anonymous author of a letter delivered to three journalists in the parliamentary press gallery attacking Mr Goff and talking about internal problems in Labour.

The letter says there is "growing discontent in the caucus with both Goff’s leadership style and his poor polling. David Cunliffe has a big smile on his face and many in the caucus now expect a move against Goff and King before the election."

"The contents of the letter, while not true, was designed to damage the party that I lead," says Mr Goff.

"It was stupid. It was disloyal."

And it was ham-fisted - the letter was circulated in the internal mail. Mr Carter was caught out because his colleagues recognised his handwriting.

Mr Goff flew back from Auckland and confronted him - but Mr Carter failed to tell the truth.

"I confronted Mr Carter with my view that it was he who circulated the letter," says Mr Goff. "He first denied it, and then when pushed he admitted it."

The letter was a direct challenge to Mr Goffs leadership - so we asked, is it safe?

"The decision to suspend him was unanimous, so that shows you exactly where caucus stands on that issue," says Mr Goff.

MP George Hawkins was also implicated in the letter, which said the Manurewa MP was threatening a by-election if a Labour Party candidate stood against him in his electorate.

"I've heard all sorts of rumours," says Mr Hawkins. "Come back in the new year and I'll tell you."

Which didn't sound like he was ruling it out - but tonight at least all eyes are on the fall from grace of one MP. The question now is this the end of the road for Mr Carter?